This invention relates to polyetherpolycarbonate copolymers. More particularly, the invention relates to poly(aryl ether/thioether)-poly(aryl carbonate) block copolymers and to the preparation of such block copolymers.
Polycarbonates are well-known commercially available resinous materials having a variety of applications. They are typically prepared by the reaction of dihydroxy compounds and a carbonate precursor, such as phosgene. The polycarbonates are high temperature, high performance thermoplastic engineering polymers with a good combination of thermal and mechanical properties, especially when the polymer is prepared from one or more aromatic diols. However, the polycarbonates do exhibit relatively poor hydrolytic stability and poor solvent resistance, particularly when exposed to humid environments for prolonged times and/or at elevated temperatures.
Attempts to modify the properties of polycarbonates resins by blending with other polymeric materials are quite often unsatisfactory because of the incompatibility of the polycarbonates with other resinous materials. To overcome this problem, it has been proposed to polymerize other resinous materials into the polycarbonate molecule. Thus, random, block and graft copolymers of polycarbonates and other polymers, such as polyethers, are known. For example, polyether sulfone has been interpolymerized into the polycarbonate molecule by preparing a hydroxyl-terminated polyether sulfone and condensing it with 2,2-bis-(4-hydroxyphenyl)-propane (Bisphenol A) using phosgene in the presence of a catalyst, and also by the pyridine-catalyzed reaction of chloroformate-terminated polycarbonate with hydroxyl-terminated polyether sulfone in a common solvent.
Poly(aryl ether/thioether)-poly(aryl carbonate) copolymers may also be prepared by combining a hydroxyl-terminated polyether/thioether sulfone and a Bisphenol A polycarbonate, and extending the copolymer to a high molecular weight by phosgenation in a common solvent: ##STR1## See McGrath, et al., Amer. Chem. Soc., Polymer Reprints, 19(1), p. 109 (1978).
In each of these methods, a carbonate radical links the polycarbonate and polyether/thioether blocks.